Deadband and resolution cause sustained equal amplitude oscillations called limit cycles that cannot be eliminated by controller tuning. A resolution limit causes limit cycles if there is integrating action at just one point in the control loop either in the process (e.g. level), positioner, or the process controller (e.g. PID).
Because of travel commitments, I have not been actively blogging. Yesterday nite, I gave a presentation at the IEEE Industry Applications Society in Concord, CA. Today, I am flying to Albuquerque to give an invited presentation to an Air Force Cyber Security and Surety meeting.
Here's the link to Walt's pix from ABB World. More to come.
10:21 a.m. #APW10 Terwiesch gives a major tech update. I will post on Soundoff soon.
9:41 a.m. #APW10 Santacana announces intent to build new $90 m high voltage cable factory in USA. Site select by Q3 and online by 2012.